CN113979967A

CN113979967A - Method for catalytic synthesis of accelerator CBS by ionic liquid protective agent

Info

Publication number: CN113979967A
Application number: CN202111607079.0A
Authority: CN
Inventors: 陆平; 李霞; 刘海良
Original assignee: Kemai Chemical Co Ltd
Current assignee: Kemai Chemical Co Ltd
Priority date: 2021-12-27
Filing date: 2021-12-27
Publication date: 2022-01-28
Anticipated expiration: 2041-12-27
Also published as: WO2023123753A1; CN113979967B

Abstract

The invention belongs to the field of rubber additives, and particularly relates to a method for catalytically synthesizing accelerator CBS by using an ionic liquid protective agent, which comprises the following steps: sequentially adding ionic liquid, MBT, cyclohexylamine, methylbenzene and water into a reaction kettle, dropwise adding a sodium hypochlorite oxidant, taking a small amount of reaction liquid when the sodium hypochlorite oxidant is about to finish titration, detecting an oxidation end point by using 2-5% copper acetate, stopping dropwise adding the oxidant after the oxidation end point is reached, continuously stirring for 10 minutes, re-detecting the oxidation end point, and stopping reaction after the oxidation end point is qualified. The method utilizes the added latam reagent ionic liquid as [ Bmim ] OH, and can realize the core problem of product quality of low amine feeding ratio feeding.

Description

Method for catalytic synthesis of accelerator CBS by ionic liquid protective agent

Technical Field

The invention belongs to the field of rubber additives, and particularly relates to a method for catalytically synthesizing accelerator CBS by using an ionic liquid protective agent.

Background

The chemical name of the rubber vulcanization accelerator CBS is N-cyclohexyl-2-benzothiazole hypoxanthamide, which is a slow-acting vulcanization accelerator widely used at home and abroad and has the advantages of short vulcanization time and excellent scorch resistance.

At present, the domestic production scheme is generally a hydrogen peroxide oxidation method and a sodium hypochlorite oxidation method, MBT (2-mercaptobenzothiazole) is adopted as a raw material to be mixed with a cyclohexylamine aqueous solution, and an oxidant is added dropwise to be oxidized to obtain the compound, wherein the oxidant mainly adopts sodium hypochlorite or hydrogen peroxide.

When sodium hypochlorite or hydrogen peroxide is used for oxidation, the raw material MBT can generate side reaction to produce benzothiazole sulfonate, so the feeding ratio of cyclohexylamine needs to be improved, the MBT and excessive cyclohexylamine generate cyclohexylamine salt of the MBT, and the raw material MBT in a reaction system is protected from being oxidized into byproducts by an oxidant so as to achieve the purpose of improving the product yield. The suitable feeding molar ratio of domestic manufacturers at present is cyclohexylamine: MBT =2.2: 1. The excessive cyclohexylamine needs to be recovered by distillation, and because the cyclohexylamine and water have azeotropy, a large amount of energy is consumed by evaporating the excessive cyclohexylamine, so that the method belongs to a high-energy-consumption process.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a method for synthesizing a promoter CBS by using an ionic liquid protective agent.

In order to achieve the purpose, the invention adopts the technical scheme that:

a method for synthesizing promoter CBS catalyzed by ionic liquid protective agent comprises the following steps: sequentially adding ionic liquid, MBT, cyclohexylamine, methylbenzene and water into a reaction kettle, dropwise adding a sodium hypochlorite oxidant, taking a small amount of reaction liquid when the sodium hypochlorite oxidant is about to finish titration, detecting an oxidation end point by using 2-5% copper acetate, stopping dropwise adding the oxidant after the oxidation end point is reached, continuously stirring for 10 minutes, re-detecting the oxidation end point, and stopping reaction after the oxidation end point is qualified.

The molar ratio of the cyclohexylamine to the MBT is 1.2-1.8: 1.

The molar ratio of the cyclohexylamine to the MBT is 1.5: 1.

The ionic liquid is [ Bmim ] OH.

The mass ratio of the ionic liquid to the MBT is 15-25: 40.

The mass ratio of the ionic liquid to the MBT is 1: 2.

Compared with the prior art, the invention has the beneficial effects that:

the method has the advantages that the product quality core problem of low amine feeding ratio feeding can be realized by using the added latamine reagent ionic liquid as [ Bmim ] OH; compared with the prior art that the mixture of strong acid cation resin and weak base anion resin is used as a catalyst and air is used as an oxidant for reaction, the method for reducing the consumption of the cyclohexylamine by distillation has the advantages that the sodium hypochlorite oxidant is safer in construction, the safety risk of the air as the oxidant is avoided, meanwhile, [ Bmim ] OH can be recycled for multiple times without influencing the catalytic performance of the [ Bmim ] OH, the amine dosage per time is reduced, and the amine recovery evaporation capacity per time is reduced.

Detailed Description

In order to make those skilled in the art better understand the technical solution of the present invention, the following provides a detailed description of the present invention with reference to the embodiments.

Example (b): the embodiment provides a method for producing CBS by using an ionic liquid protective agent, which comprises the following steps:

(1) sequentially adding ionic liquid, MBT, cyclohexylamine, methylbenzene and water into a reaction kettle, controlling a certain molar ratio, dropwise adding a sodium hypochlorite oxidant, taking a small amount of reaction liquid when the sodium hypochlorite oxidant is about to titrate, detecting an oxidation end point by using 2-5% copper acetate, stopping dropwise adding the oxidant after the oxidation end point is reached, continuously stirring for 10 minutes, re-detecting the oxidation end point, and stopping reaction after the oxidation end point is qualified. After the reaction is finished, the composition of the product is analyzed by organic phase liquid chromatography.

(2) The analytical data for different amine loadings are shown in table 1.

TABLE 1

The MBT conversion results are shown in table 2.

TABLE 2

When the amine adding ratio is considered comprehensively to be 1.5, the product yield and the purity of the crystallized product reach the best, and the product meets the quality requirement of national standard products.

(3) The analytical data of different ionic liquid ratios are shown in table 3, and the results are shown in table 4.

TABLE 3

TABLE 4

(4) Ionic liquid application investigation: the ionic liquid and the organic phase after liquid separation are used indiscriminately, the raw material cyclohexylamine and the raw material MBT are supplemented according to the amine adding ratio of 1.5, the indiscriminate use result is continuously inspected, as shown in Table 5, the sample mixing analysis is performed every 5 times, and the indiscriminate use period is totally inspected for 30 times.

TABLE 5

After 30 times, the activity, selectivity and yield of the ionic liquid are not reduced, and the application requirement is met.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. The method for catalytically synthesizing the promoter CBS by using the ionic liquid protective agent is characterized by comprising the following steps of: sequentially adding ionic liquid, MBT, cyclohexylamine, methylbenzene and water into a reaction kettle, dropwise adding a sodium hypochlorite oxidant, taking a small amount of reaction liquid when the sodium hypochlorite oxidant is about to finish titration, detecting an oxidation end point by using 2-5% copper acetate, stopping dropwise adding the oxidant after the oxidation end point is reached, continuously stirring for 10 minutes, re-detecting the oxidation end point, and stopping reaction after the oxidation end point is qualified.

2. The method for catalytic synthesis of accelerator CBS with ionic liquid protectant according to claim 1, wherein the molar ratio of cyclohexylamine to MBT is 1.2-1.8: 1.

3. The method for catalytic synthesis of accelerator CBS with ionic liquid protectant according to claim 1, wherein the molar ratio of cyclohexylamine to MBT is 1.5: 1.

4. The method for catalytic synthesis of accelerator CBS with ionic liquid protectant according to claim 1, wherein the ionic liquid is [ Bmim ] OH.

5. The method for catalytic synthesis of accelerator CBS with ionic liquid protectant as claimed in claim 1, wherein the mass ratio of ionic liquid to MBT is 15-25: 40.

6. The method of claim 1, wherein the mass ratio of the ionic liquid to the MBT is 1: 2.